Differential expression of CCR3 and CXCR3 by human lung and bone marrow‐derived mast cells: implications for tissue mast cell migration

The selective microlocalization of mast cells within specific airway structures, such as the airway smooth muscle and submucosal glands, in asthma is important in the pathophysiology of inflammatory lung disease. Chemokines are likely candidates mediating mast cell migration into these tissue compartments. In this study, we have defined the chemokine receptor profile of human lung mast cells (HLMC) compared with mast cells derived from human bone marrow (BM) and the human mast cell line HMC‐1. CXC chemokine receptor 3 (CXCR3) was the most highly expressed chemokine receptor on ex vivo HLMC analyzed by flow cytometry, and CXCR3 expression by mast cells in the bronchial mucosa was confirmed by immuno‐histochemistry. CXCR3 was functional, inducing a rise in cytosolic‐free Ca2+, actin reorganization, and chemotaxis in response to the CXC ligands CXCL9, ‐10, and ‐11. CXCR3 activation did not induce degranulation or cytokine synthesis. In addition, more than 10% of ex vivo HLMC expressed CC chemokine receptor 3, CXCR1, and CXCR4. It is interesting that CXCR3 was not expressed by human BM‐derived mast cells, suggesting its expression is induced during tissue maturation. As CXCR3 ligands are elevated in many pulmonary diseases, CXCR3 may be important for determining the anatomical microlocalization of mast cells within the human lung.